diff --git a/static/app/utils/replays/hooks/useReplayData.spec.tsx b/static/app/utils/replays/hooks/useReplayData.spec.tsx
index 67a4e08fdaf957..55570bb95e744a 100644
--- a/static/app/utils/replays/hooks/useReplayData.spec.tsx
+++ b/static/app/utils/replays/hooks/useReplayData.spec.tsx
@@ -5,19 +5,35 @@ import {reactHooks} from 'sentry-test/reactTestingLibrary';
 
 import useReplayData from 'sentry/utils/replays/hooks/useReplayData';
 import ReplayReader from 'sentry/utils/replays/replayReader';
+import useProjects from 'sentry/utils/useProjects';
 import type {ReplayRecord} from 'sentry/views/replays/types';
 
 jest.useFakeTimers();
 jest.spyOn(ReplayReader, 'factory');
+jest.mock('sentry/utils/useProjects');
 
 const {organization, project} = initializeOrg();
 
+const mockUseProjects = useProjects as jest.MockedFunction<typeof useProjects>;
+mockUseProjects.mockReturnValue({
+  fetching: false,
+  projects: [project],
+  fetchError: null,
+  hasMore: false,
+  initiallyLoaded: true,
+  onSearch: () => Promise.resolve(),
+  placeholders: [],
+});
+
 const MockedReplayReaderFactory = ReplayReader.factory as jest.MockedFunction<
   typeof ReplayReader.factory
 >;
 
 function getMockReplayRecord(replayRecord?: Partial<ReplayRecord>) {
-  const HYDRATED_REPLAY = TestStubs.ReplayRecord(replayRecord);
+  const HYDRATED_REPLAY = TestStubs.ReplayRecord({
+    ...replayRecord,
+    project_id: project.id,
+  });
   const RAW_REPLAY = {
     ...HYDRATED_REPLAY,
     duration: HYDRATED_REPLAY.duration.asSeconds(),
@@ -45,7 +61,7 @@ describe('useReplayData', () => {
     });
 
     MockApiClient.addMockResponse({
-      url: `/projects/${organization.slug}/${project.slug}/replays/${mockReplayResponse.id}/`,
+      url: `/organizations/${organization.slug}/replays/${mockReplayResponse.id}/`,
       body: {data: mockReplayResponse},
     });
 
@@ -87,7 +103,7 @@ describe('useReplayData', () => {
     ];
 
     MockApiClient.addMockResponse({
-      url: `/projects/${organization.slug}/${project.slug}/replays/${mockReplayResponse.id}/`,
+      url: `/organizations/${organization.slug}/replays/${mockReplayResponse.id}/`,
       body: {data: mockReplayResponse},
     });
     const mockedSegmentsCall1 = MockApiClient.addMockResponse({
@@ -155,7 +171,7 @@ describe('useReplayData', () => {
     ];
 
     MockApiClient.addMockResponse({
-      url: `/projects/${organization.slug}/${project.slug}/replays/${mockReplayResponse.id}/`,
+      url: `/organizations/${organization.slug}/replays/${mockReplayResponse.id}/`,
       body: {data: mockReplayResponse},
     });
     const mockedErrorsCall1 = MockApiClient.addMockResponse({
@@ -214,7 +230,7 @@ describe('useReplayData', () => {
 
     const mockedReplayCall = MockApiClient.addMockResponse({
       asyncDelay: 1,
-      url: `/projects/${organization.slug}/${project.slug}/replays/${mockReplayResponse.id}/`,
+      url: `/organizations/${organization.slug}/replays/${mockReplayResponse.id}/`,
       body: {data: mockReplayResponse},
     });
 
@@ -292,4 +308,34 @@ describe('useReplayData', () => {
       errors: mockErrorResponse,
     });
   });
+
+  it('should handle a replaySlug without projectSlug', async () => {
+    const {mockReplayResponse, expectedReplay} = getMockReplayRecord({
+      count_errors: 0,
+      count_segments: 0,
+      error_ids: [],
+    });
+
+    MockApiClient.addMockResponse({
+      url: `/organizations/${organization.slug}/replays/${mockReplayResponse.id}/`,
+      body: {data: mockReplayResponse},
+    });
+
+    const {result, waitForNextUpdate} = reactHooks.renderHook(useReplayData, {
+      initialProps: {
+        replaySlug: mockReplayResponse.id,
+        orgSlug: organization.slug,
+      },
+    });
+
+    await waitForNextUpdate();
+
+    expect(result.current).toEqual({
+      fetchError: undefined,
+      fetching: false,
+      onRetry: expect.any(Function),
+      replay: expect.any(ReplayReader),
+      replayRecord: expectedReplay,
+    });
+  });
 });
diff --git a/static/app/utils/replays/hooks/useReplayData.tsx b/static/app/utils/replays/hooks/useReplayData.tsx
index 01d6362b51fde9..88941a0d7a2080 100644
--- a/static/app/utils/replays/hooks/useReplayData.tsx
+++ b/static/app/utils/replays/hooks/useReplayData.tsx
@@ -6,6 +6,7 @@ import {mapResponseToReplayRecord} from 'sentry/utils/replays/replayDataUtils';
 import ReplayReader from 'sentry/utils/replays/replayReader';
 import RequestError from 'sentry/utils/requestError/requestError';
 import useApi from 'sentry/utils/useApi';
+import useProjects from 'sentry/utils/useProjects';
 import type {ReplayError, ReplayRecord} from 'sentry/views/replays/types';
 
 type State = {
@@ -94,7 +95,8 @@ function useReplayData({
   errorsPerPage = 50,
   segmentsPerPage = 100,
 }: Options): Result {
-  const [projectSlug, replayId] = replaySlug.split(':');
+  const replayId = parseReplayId(replaySlug);
+  const projects = useProjects();
 
   const api = useApi();
 
@@ -103,18 +105,23 @@ function useReplayData({
   const [errors, setErrors] = useState<ReplayError[]>([]);
   const [replayRecord, setReplayRecord] = useState<ReplayRecord>();
 
+  const projectSlug = useMemo(() => {
+    if (!replayRecord) {
+      return null;
+    }
+    return projects.projects.find(p => p.id === replayRecord.project_id)?.slug;
+  }, [replayRecord, projects.projects]);
+
   // Fetch every field of the replay. We're overfetching, not every field is used
   const fetchReplay = useCallback(async () => {
-    const response = await api.requestPromise(
-      `/projects/${orgSlug}/${projectSlug}/replays/${replayId}/`
-    );
+    const response = await api.requestPromise(makeFetchReplayApiUrl(orgSlug, replayId));
     const mappedRecord = mapResponseToReplayRecord(response.data);
     setReplayRecord(mappedRecord);
     setState(prev => ({...prev, fetchingReplay: false}));
-  }, [api, orgSlug, projectSlug, replayId]);
+  }, [api, orgSlug, replayId]);
 
   const fetchAttachments = useCallback(async () => {
-    if (!replayRecord) {
+    if (!replayRecord || !projectSlug) {
       return;
     }
 
@@ -147,7 +154,7 @@ function useReplayData({
       })
     );
     setState(prev => ({...prev, fetchingAttachments: false}));
-  }, [segmentsPerPage, api, orgSlug, projectSlug, replayRecord]);
+  }, [segmentsPerPage, api, orgSlug, replayRecord, projectSlug]);
 
   const fetchErrors = useCallback(async () => {
     if (!replayRecord) {
@@ -233,4 +240,24 @@ function useReplayData({
   };
 }
 
+// see https://github.com/getsentry/sentry/pull/47859
+// replays can apply to many projects when incorporating backend errors
+// this makes having project in the `replaySlug` obsolete
+// we must keep this url schema for now for backward compat but we should remove it at some point
+// TODO: remove support for projectSlug in replay url?
+function parseReplayId(replaySlug: string) {
+  const maybeProjectSlugAndReplayId = replaySlug.split(':');
+  if (maybeProjectSlugAndReplayId.length === 2) {
+    return maybeProjectSlugAndReplayId[1];
+  }
+
+  // if there is no projectSlug then we assume we just have the replayId
+  // all other cases would be a malformed url
+  return maybeProjectSlugAndReplayId[0];
+}
+
+function makeFetchReplayApiUrl(orgSlug: string, replayId: string) {
+  return `/organizations/${orgSlug}/replays/${replayId}/`;
+}
+
 export default useReplayData;